Since this ruling is NOT allowed to be argued, will a warning be issued to a person wanting to discuss or argue this hit by pitch rule?

Yes, the umpire should hold up his hand and warn the coach not to proceed and argue, as this is ball & strikes. In games with instant replay, the coach can inform the umpire he would like to challenge this HBP, if he has a challenge available in innings 1-7, Crew Chief can go to review 8th inning & beyond